EFFECTS OF THE GABA(B) ANTAGONIST CGP-35348 ON SLEEP-WAKE STATES, BEHAVIOR, AND SPIKE-WAVE DISCHARGES IN OLD RATS

The GABA(B) antagonist CGP 35348 was intraperitoneally given in doses of 100, 300, and 900 mg/kg to old rats. These rats were earlier chroni cally provided with EEG and EMG electrodes, Sleep recordings based on visual inspection of EEG and EMG recordings were made for 3 h post inj ection, and spontaneous behaviour in the recording cage was additional ly observed, With 100 and 300 mg/kg, the drug produced an increase in the duration of REM sleep compared to the saline-injected control grou p. The REM sleep latency was correspondingly reduced. Non-REM sleep an d total sleep duration increased and an s-shaped dose-response relatio nship was found. Explorative behaviour was diminished after injections with 100 and 300 mg/kg CGP 35348, The number and duration of spike-wa ve discharges were reduced after all doses of CGP 35348 and during all 3 recording hours, The latter outcomes confirm the strong suppressive action of this drug on spike-wave discharges; these effects have also been reported in models of absence epilepsy, The hypnotic properties and especially the increase in REM sleep after the administration of C GP 35348 deserve attention considering the paucity of drugs which faci litate REM sleep. The discovery of drugs promoting REM sleep might hav e theoretical as well as clinical consequences.